The present invention relates to a portable machine tool, especially a hammer drill, which comprises a preferably electric drive motor rotating over a gear transmission a turning sleeve and tool receiving means connected thereto in which a tool is guided, and which drives further a striking mechanism which includes an axially reciprocatable drive piston, a coaxial beater driven, preferably over an air pillow, from the drive piston, and in which the beater transmits its striking energy onto the tool.
Such a portable machine tool is, for instance, known from the DE-OS No. 24 49 191. In this known construction the drive motor drives a pinion on the motor shaft and a gear meshing therewith drives a wobble plate which forms part of the striking mechanism. The wobble plate is mounted on a counter shaft for rotation therewith, which carries a further pinion meshing with a gear connected to the turning sleeve. The turning sleeve itself is likewise provided with a gearing which meshes with the gearing of a boring spindle of the tool receiver for rotating the latter.
Such a construction in which the striking energy from the beater is transmitted to the tool through intermediate members, such as the boring spindle, results in a relatively large construction length of the machine tool and therewith connected increased cost. Such intermediate members will also increase the total weight of the machine tool. An additional essential disadvantage is further that, due to the great mass of such intermediate members, the efficiency of the transmission of the striking energy of the tool is greatly reduced.